The Sultanate of Oman is experiencing spectacular demographic transition in recent time. Current fertility rate has declined dramatically from a very high rate of 8.6 births per women in 1988 to 3.3 births per woman in 2008, a decline of 5.3 births per woman or 62% decline within a short span of 20 years. This paper provides critical review of the fertility transition in Oman and identify the direct and indirect determinants of declining fertility using national level health and fertility survey data. Increase in age at marriage followed by contraceptive use are the most important factors determining fertility in Oman. Post-partum infecundability also play important role in fertility control in Oman. Women education and employment are likely factors that encourage couples to delay marriage, spacing birth by using modern family planning methods and thus reduce fertility desire. The decline in fertility in Oman is strongly related to socio-economic development.